HF AND VHF QUARTZ-FILTER-CRYSTAL DESIGN CONSIDERATIONS.
Abstract
Studies into the problems associated with the design of quartz filter crystals in the HF and VHF range have resulted in design data for producing crystal units with a wide range of equivalent cirucit parameters while still maintaining a suppression of unwanted modes to approximately 40 db. To plate thickness ration together with the total mass deposition. In essence, to obtain a wide range of the equivalent electric circuit parameters, it is necessary to vary the electrode size. An adequate suppression of unwanted modes is assured by a proper selection of mass loading. The proper choice of mass loading one must use has been investigated extensively at this Command in an effort to determine, first, the optimum plating thickness which will give the required mass loading for maximum suppression of unwanted modes, and secondly, to determine the range of electrode thicknesses that can be used on either side of this optimum, and still maintain a 40 db suppression, i.e., amplitude of unwanted modes vs. plate back information. Having this, a criterion can be established on the tolerance of the unplated wafer frequency. Design information resulting from these investigations with filter crystals operating on the fundamental and fifth overtone is presented.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1965
- Accession Number
- AD0623507
Entities
People
- Theodore J. Lukaszek
Organizations
- United States Army Communications-Electronics Command